Method and apparatus for cleaning process monitoring

ABSTRACT

A cleaning process monitoring system, comprising: a cleaning container comprising an inlet for receiving a cleaning solution and an outlet for draining a waste solution; a particle detector coupled to the outlet and configured to measure a plurality of particle parameters associated with the waste solution so as to provide a real-time monitoring of the cleaning process; a pump coupled to the cleaning container and configured to provide suction force to draw solution through the cleaning system; a controller coupled to the pump and the particle detector and configured to receive the plurality of particle parameters from the particle detector and to provide control to the cleaning system; and a host computer coupled to the controller and configured to provide at least one control parameter to the controller.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to U.S. Provisional PatentApplication No. 62/585,746, filed on Nov. 14, 2017, which isincorporated by reference herein in its entirety.

BACKGROUND

With the rapid shrinking of device dimensions and the strictrequirements of achieving extremely smooth surfaces, there is anincreasing need for global surface planarization of various thin filmsin the front- and back-end processes using chemical mechanicalplanarization (CMP). During CMP, the pad material and the wafer surfaceare in intimate contact in the presence of slurry. The slurry particlesremain on the wafer surface at the end of the CMP process, and if notremoved, they can cause various types of defects (scratches, corrosionspots, etc.) in the subsequent processing steps, which affects thefunctionalization of the integrated circuit (IC). These defects, in someinstances, may also arise from the pad and the diamond disc conditioner.The other common forms of contaminants include organic residues andmetallic impurities. The residues typically originate from slurryadditives or the pad material and require subsequent processing such asplasma ashing or an oxidant (e.g., peroxide)-based chemical cleaning.The metallic impurities that are left on the surface in concentrationsof 10¹¹-10¹² atoms cm⁻² emanate either from abrasion caused to the metallines or from metal ions present in the slurry. Particulatecontamination in the form of abrasive particles, precipitates, orfragments of films and pad can enhance local surface roughness, impactthe photolithography process by blocking the UV light, or cause shortingwhen the particles are conductive. Metallic impurities can affectelectrical characteristics when they are highly mobile or causedissolution of silicon in the case of more noble metal ions. Organicresidues influence the wettability of the films and reduce the adhesionof deposited films. In an effort to significantly lower the defectdensity on various films prior to the next processing step, the demandfor an effective and efficient post-CMP cleaning process has beencontinuously rising.

Among all possible forces, the dominant ones are van der Waals adhesionforces from dipole-dipole interactions and double-layer interactionsfrom adsorption of specific ions in the solution due to their highermagnitude compared to other forces for the same size of the particle.

Different post-CMP cleaning methods are used for removal of particles,organic, and metal such as, for example batch cleaning of a cassette ofwafers which involves rinsing and megasonic cleaning in chemicalsfollowed by rinsing with DI water and single wafer cleaning using brushscrubber and/or megasonic actuators. Despite of different cleaningmethods, different cleaning chemistries are selected based on thepotential type of contaminations from the previous deposition process orCMP process, as well as the material of the surface. All cleaningmethods involve the use of liquid chemicals with various chemicalcompositions and traditionally, the cleaning design is based onexperiment and time when the configuration to other parameters are fixede.g., solution temperature, solution pH, rotation speed, contactdistance, contact pressure, actuator power, actuation frequency and etc.Furthermore, to ensure a near-complete particle removal, excessivechemicals and time are dedicated yet wasted. Therefore, there exists aneed for the development of a method and a system for end pointdetection in a post-CMP cleaning process.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that various features are not necessarily drawn to scale. In fact,the dimensions and geometries of the various features may be arbitrarilyincreased or reduced for clarity of illustration.

FIG. 1 illustrates a block diagram showing an exemplary configuration ofa cleaning processing monitoring system integrated to a post-CMPcleaning system, in accordance with some embodiments of the presentdisclosure.

FIG. 2 illustrates a block diagram of the controller of the system shownin FIG. 1, in accordance with some embodiments of the presentdisclosure.

FIG. 3 illustrate a flowchart of a method to perform a cleaning processmonitoring in a post CMP cleaning process, in accordance with variousembodiments.

FIG. 4 illustrates an exemplary data showing concentrations of particlesof various sizes versus cleaning time, in accordance with variousembodiments of the present disclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following disclosure describes various exemplary embodiments forimplementing different features of the subject matter. Specific examplesof components and arrangements are described below to simplify thepresent disclosure. These are, of course, merely examples and are notintended to be limiting. For example, it will be understood that when anelement is referred to as being “connected to” or “coupled to” anotherelement, it may be directly connected to or coupled to the otherelement, or one or more intervening elements may be present.

The presented disclosure provides various embodiments of a method and asystem for cleaning process monitoring during a post-CMP cleaning. Suchsystem can be integrated to a cleaning container or cleaning apparatusat a downstream of the cleaning solution (e.g., in a drain pipe). Bymonitoring the particle level including particle size and number andcomparing the measured particle level to a required particle level, acleaning end point can be detected. Based on the real-time monitoring ofthe particle level, cleaning time can be adjusted accordingly. Thismethod allows an effective cleaning of the substrate with customizedcleaning time without over cleaning the wafer surface such that thecleaning damage can be minimized. At the same time, this method reducesthe amount of chemical waste generated and reduce the cleaning time inthe entire manufacturing process. Most importantly, this method allowsto maximize the production yield by assuring an effective cleaning oneach substrate after CMP. Accordingly, the above-mentioned issues maybeadvantageously avoided.

This description of the exemplary embodiments is set to be understood inconnection with the figures of the accompanying drawing, which are to beconsidered part of the entire written description. In the description,relative terms such as “lower,” “upper,” “horizontal,” “vertical,”“above,” “below,” “up,” “down,” “top” and “bottom” as well asderivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,”etc.) should be construed to refer to the orientation as then describedor as shown in the drawing under discussion. These relative terms arefor convenience of description and do not require that the apparatus beconstructed or operated in a particular orientation.

The presented disclosure provides various embodiments of a method and asystem for detecting endpoint in a post-chemical-mechanicalplanarization process. During the post-CMP cleaning process, a number ofsteps in which a rinsing process is used can be integrated with thispresented real-time end point detection system. This presented real-timecontinuous monitoring system is integrated to the drain pipelines ofcleaning containers. By analyzing the drain solution and monitoring theparticle concentration therein, the cleaning process for differentwafers can be customized based on their own needs for cleaning ratherthan using a predefined recipe for all wafers. On one hand, thispresented system can ensure a high-quality cleaning and on the otherhand, it can reduce the cleaning time and minimize the chemical wastecreated in the cleaning process. Accordingly, the above-mentionedenvironmental and security issues maybe advantageously avoided.

FIG. 1 illustrates a block diagram showing an exemplary configuration ofa cleaning processing monitoring system 100 integrated to a post-CMPcleaning system, in accordance with some embodiments of the presentdisclosure. The monitoring system 100 comprises a rinsing solutionsupply 102, a chemical supply 104, a cleaning container 106, a particledetector 108 connected to the container 106 through a drain pipe 107, aneffluent pump 110, an effluent reservoir 112, a controller 114 and ahost computer 116, according to some embodiments. The rinsing solutionfrom the rinsing solution supply 102 enters the container 106 through afirst input port. In some embodiment, the rinsing solution can bedeionized (DI) water. The chemical supply 104 may contain surfactants,ammonium hydroxide (NH4OH) solution, isopropanol (IPA), methanol,hydrofluoric (HF) acid, citric acid, tetraethyl ammonium hydroxide(TMAH), hydrogen peroxide, and etc., according to the particular slurryand/or contaminants that are involved in the CMP process. The chemicalfrom the chemical supply 104 enters the cleaning container 106 through asecond input port. In some embodiments, the rinsing solution (e.g., DIwater) and chemical from the rinsing solution supply 102 and thechemical supply 104, respectively, can be premixed at a predefinedconcentration so as to prepare a cleaning solution before entering thecleaning container 106 at a single input port 103. In some embodiments,the cleaning container 106 comprises at least one cleaning head (notshown) to guide the rinsing or cleaning solution to the surface of awafer.

In some embodiments, the particle detector 108 is connected to thecleaning container 106. Effluent 118 flows through the drain pipe 107 ofthe cleaning container 106 into the particle detector 108 which countsthe number of particles per liter of effluent. The particle detector 108is further connected to a pump 110. Effluent 118 passes from thecontainer 106 to the particle detector 108 and then through the pump 110which provides the suction force to draw cleaning solution waste throughthe system 100. Finally, the effluent 118 is released to a drain or acollection reservoir 112.

In some embodiments, an ideal particle detector 108 is compatible to thecleaning chemical environment and temperature for detecting particlelevels should have the following properties, including low drift andnoise level, high sensitivity, fast response time, wide linear dynamicrange, low dead volume, insensitivity to measurement conditions (e.g.,solvent, flow rate, and temperature), simple operation, highreliability, compact size/weight, and low power consumption, inaccordance with various embodiments. In some embodiments, the particledetector 108 can be a laser-based particle counter. Typically, theparticle detector 108 has a plurality of channels that are particularlydesigned for detecting particles of different sizes. In someembodiments, the channel size of a particle detector 108 can be at leastone of the following: 20, 50, 70, 100, 150, 200 and 500 nm. In someembodiments, the flow rate for a particle detector 108 can be in a rangeof 10 milliliter per minute (mL/min) to 1 liter per minute (L/min).Selection of the particle detector 108 are determined by application,for example the particle concentration and typical particle sizes thatare involved in the fabrication process. In some embodiments, theparticle detector 108 can be an Ultrachem 100 liquid particle counter.

In some embodiments, the particle detector 108 is electrically coupledto a controller 114 and a host computer 116. Concentrations of particlesof various sizes can be measured in real-time and then transmitted fromthe particle detector 108 to the controller 114 and then displayed onthe host computer 116 in a predetermined format. The particleconcentration in the effluent 118 in the downstream pipe is thencompared to a pre-defined value in the controller 114. When the particleconcentration is greater than the pre-defined value, the controller 114continues the cleaning process by properly operating the controlelements (e.g., valves, heaters, etc) on the rinsing solution supply102, chemical supply 104, the rinsing apparatus in the cleaningcontainer 106 and the pump 110, such that the cleaning time can beadjusted according to the measured particle concentration. When theparticle concentration is equal to or smaller than the pre-definedvalue, the controller 114 continues the cleaning process in a similarfashion described above by a pre-defined time period and terminates thecleaning process such that the wafer can then be unloaded from thecleaning container to the next step of the fabrication process, e.g., anext cleaning step or a next fabrication step. In some embodiments, thepre-defined value can be 10000 particles per milliliter.

In some embodiments, the host computer 116 configures at least onecontrol parameter to the controller 114 including ramping speed,response time, etc. In some embodiments, the controller 114 can adjustthe pump speed in the downstream to provide an optimized condition,including flow rate and pressure for the particle detector 108 toproperly detect different particles sizes and concentrations. In someembodiments, the controller 114 can also adjust the flow using a flowcontroller/regulator (not shown) in the particle detector 108.

FIG. 2 illustrates a block diagram of the controller 114 of the system100 shown in FIG. 1, in accordance with some embodiments of the presentdisclosure. The controller 114 in the system 100 may comprise aprocessor, a memory, an input/output interface (hereinafter “I/Ointerface”), a communications interface, and a system bus. In someembodiments, components in these units in the system 100 may be combinedor omitted such as, for example, not including the communicationsinterface. In some embodiments, the controller 114 of the system 100 maycomprise other components not shown in FIG. 2. For example, thesecontroller 114 of the system 100 also may comprise a power subsystemproviding power to the light source. In other embodiments, thesecontroller 114 of the system 100 may comprise several instances of thecomponents shown in FIG. 2.

The processor 212 may comprise any processing circuitry operative tocontrol the operations and performance of the controller 114 of thesystem 100. In various aspects, the processor 212 may be implemented asa general purpose processor, a chip multiprocessor (CMP), a dedicatedprocessor, an embedded processor, a digital signal processor (DSP), anetwork processor, an input/output (I/O) processor, a media accesscontrol (MAC) processor, a radio baseband processor, a co-processor, amicroprocessor such as a complex instruction set computer (CISC)microprocessor, a reduced instruction set computing (RISC)microprocessor, and/or a very long instruction word (VLIW)microprocessor, or other processing device. The processor subsystem 406also may be implemented by a controller, a microcontroller, anapplication specific integrated circuit (ASIC), a field programmablegate array (FPGA), a programmable logic device (PLD), and so forth.

In various aspects, the processor 212 may be arranged to run anoperating system (OS) and various applications. Examples of an OScomprise, for example, operating systems generally known under the tradename of Apple OS, Microsoft Windows OS, Android OS, and any otherproprietary or open source OS. Examples of applications comprise, forexample, a telephone application, a camera (e.g., digital camera, videocamera) application, a browser application, a multimedia playerapplication, a gaming application, a messaging application (e.g., email,short message, multimedia), a viewer application, and so forth.

In some embodiments, at least one non-transitory computer-readablestorage medium is provided having computer-executable instructionsembodied thereon, wherein, when executed by at least one processor, thecomputer-executable instructions cause the at least one processor toperform embodiments of the methods described herein. Thiscomputer-readable storage medium can be embodied in the memory 213.

In some embodiments, the memory 213 may comprise any machine-readable orcomputer-readable media capable of storing data, including bothvolatile/non-volatile memory and removable/non-removable memory. Thememory 213 may comprise at least one non-volatile memory unit. Thenon-volatile memory unit is capable of storing one or more softwareprograms. The software programs may contain, for example, applications,user data, device data, and/or configuration data, or combinationstherefore, to name only a few. The software programs may containinstructions executable by the various components of the controller 114of the system 100.

For example, memory 213 may comprise read-only memory (ROM),random-access memory (RAM), dynamic RAM (DRAM), Double-Data-Rate DRAM(DDR-RAM), synchronous DRAM (SDRAM), static RAM (SRAM), programmable ROM(PROM), erasable programmable ROM (EPROM), electrically erasableprogrammable ROM (EEPROM), flash memory (e.g., NOR or NAND flashmemory), content addressable memory (CAM), polymer memory (e.g.,ferroelectric polymer memory), phase-change memory (e.g., ovonicmemory), ferroelectric memory, silicon-oxide-nitride-oxide-silicon(SONOS) memory, disk memory (e.g., floppy disk, hard drive, opticaldisk, magnetic disk), or card (e.g., magnetic card, optical card), orany other type of media suitable for storing information.

In one embodiment, the memory 213 may contain an instruction set, in theform of a file for executing a method of generating one or more timinglibraries as described herein. The instruction set may be stored in anyacceptable form of machine readable instructions, including source codeor various appropriate programming languages. Some examples ofprogramming languages that may be used to store the instruction setcomprise, but are not limited to: Java, C, C++, C#, Python, Objective-C,Visual Basic, or .NET programming. In some embodiments a compiler orinterpreter is comprised to convert the instruction set into machineexecutable code for execution by the processor 212.

In some embodiments, the I/O interface 214 may comprise any suitablemechanism or component to at least enable a user to provide input to theunits 203, 204 and 205 and the units 203, 204 and 205 to provide outputto the user. For example, the I/O interface 214 may comprise anysuitable input mechanism, including but not limited to, a button,keypad, keyboard, click wheel, touch screen, or motion sensor. In someembodiments, the I/O interface 214 may comprise a capacitive sensingmechanism, or a multi-touch capacitive sensing mechanism (e.g., a touchscreen).

In some embodiments, the I/O interface 214 may comprise a visualperipheral output device for providing a display visible to the user.For example, the visual peripheral output device may comprise a screensuch as, for example, a Liquid Crystal Display (LCD) screen,incorporated into the controller 114 of the system 100. As anotherexample, the visual peripheral output device may comprise a movabledisplay or projecting system for providing a display of content on asurface remote from the controller 114 of the system 100. In someembodiments, the visual peripheral output device can comprise acoder/decoder, also known as a Codec, to convert digital media data intoanalog signals. For example, the visual peripheral output device maycomprise video Codecs, audio Codecs, or any other suitable type ofCodec.

The visual peripheral output device also may comprise display drivers,circuitry for driving display drivers, or both. The visual peripheraloutput device may be operative to display content under the direction ofthe processor 212. For example, the visual peripheral output device maybe able to play media playback information, application screens forapplication implemented the controller 114 of the system 100,information regarding ongoing communications operations, informationregarding incoming communications requests, or device operation screens,to name only a few.

In some embodiments, the communications interface 215 may comprise anysuitable hardware, software, or combination of hardware and softwarethat is capable of coupling the controller 114 of the system 100 to oneor more networks and/or additional devices. The communications interface215 may be arranged to operate with any suitable technique forcontrolling information signals using a desired set of communicationsprotocols, services or operating procedures. The communicationsinterface 215 may comprise the appropriate physical connectors toconnect with a corresponding communications medium, whether wired orwireless.

Systems and methods of communication comprise a network, in accordancewith some embodiments. In various aspects, the network may compriselocal area networks (LAN) as well as wide area networks (WAN) includingwithout limitation Internet, wired channels, wireless channels,communication devices including telephones, computers, wire, radio,optical or other electromagnetic channels, and combinations thereof,including other devices and/or components capable of/associated withcommunicating data. For example, the communication environments comprisein-body communications, various devices, and various modes ofcommunications such as wireless communications, wired communications,and combinations of the same.

Wireless communication modes comprise any mode of communication betweenpoints (e.g., nodes) that utilize, at least in part, wireless technologyincluding various protocols and combinations of protocols associatedwith wireless transmission, data, and devices. The points comprise, forexample, wireless devices such as wireless headsets, audio andmultimedia devices and equipment, such as audio players and multimediaplayers, telephones, including mobile telephones and cordlesstelephones, and computers and computer-related devices and components,such as printers, network-connected machinery such as a circuitgenerating system, and/or any other suitable device or third-partydevice.

Wired communication modes comprise any mode of communication betweenpoints that utilize wired technology including various protocols andcombinations of protocols associated with wired transmission, data, anddevices. The points comprise, for example, devices such as audio andmultimedia devices and equipment, such as audio players and multimediaplayers, telephones, including mobile telephones and cordlesstelephones, and computers and computer-related devices and components,such as printers, network-connected machinery, and/or any other suitabledevice or third-party device. In various implementations, the wiredcommunication modules may communicate in accordance with a number ofwired protocols. Examples of wired protocols may comprise UniversalSerial Bus (USB) communication, RS-232, RS-422, RS-423, RS-485 serialprotocols, FireWire, Ethernet, Fiber Channel, MIDI, ATA, Serial ATA, PCIExpress, T-1 (and variants), Industry Standard Architecture (ISA)parallel communication, Small Computer System Interface (SCSI)communication, or Peripheral Component Interconnect (PCI) communication,to name only a few examples.

Accordingly, in various aspects, the communications interface 215 maycomprise one or more interfaces such as, for example, a wirelesscommunications interface, a wired communications interface, a networkinterface, a transmit interface, a receive interface, a media interface,a system interface, a component interface, a switching interface, a chipinterface, a controller, and so forth. When implemented by a wirelessdevice or within wireless system, for example, the communicationsinterface 215 may comprise a wireless interface comprising one or moreantennas, transmitters, receivers, transceivers, amplifiers, filters,control logic, and so forth.

In various aspects, the communications interface 215 may provide voiceand/or data communications functionality in accordance a number ofwireless protocols. Examples of wireless protocols may comprise variouswireless local area network (WLAN) protocols, including the Institute ofElectrical and Electronics Engineers (IEEE) 802.xx series of protocols,such as IEEE 802.11a/b/g/n, IEEE 802.16, IEEE 802.20, and so forth.Other examples of wireless protocols may comprise various wireless widearea network (WWAN) protocols, such as GSM cellular radiotelephonesystem protocols with GPRS, CDMA cellular radiotelephone communicationsystems with 1×RTT, EDGE systems, EV-DO systems, EV-DV systems, HSDPAsystems, and so forth. Further examples of wireless protocols maycomprise wireless personal area network (PAN) protocols, such as anInfrared protocol, a protocol from the Bluetooth Special Interest Group(SIG) series of protocols, including Bluetooth Specification versionsv1.0, v1.1, v1.2, v2.0, v2.0 with Enhanced Data Rate (EDR), as well asone or more Bluetooth Profiles, and so forth. Yet another example ofwireless protocols may comprise near-field communication techniques andprotocols, such as electro-magnetic induction (EMI) techniques. Anexample of EMI techniques may comprise passive or active radio-frequencyidentification (RFID) protocols and devices. Other suitable protocolsmay comprise Ultra Wide Band (UWB), Digital Office (DO), Digital Home,Trusted Platform Module (TPM), ZigBee, and so forth.

In some embodiments, the controller 114 of the system 100 may comprise asystem bus 216 that couples various system components including theprocessor 212, the memory 213, and the I/O interface 214. The system bus216 can be any of several types of bus structure(s) including a memorybus or memory controller, a peripheral bus or external bus, and/or alocal bus using any variety of available bus architectures including,but not limited to, 9-bit bus, Industrial Standard Architecture (ISA),Micro-Channel Architecture (MSA), Extended ISA (EISA), Intelligent DriveElectronics (IDE), VESA Local Bus (VLB), Peripheral ComponentInterconnect Card International Association Bus (PCMCIA), SmallComputers Interface (SCSI) or other proprietary bus, or any custom bussuitable for computing device applications.

FIG. 3 illustrate a flowchart of a method 300 to perform an end pointdetection in a post CMP cleaning process, in accordance with variousembodiments. It is understood that additional operations may be providedbefore, during, and after the method 300 of FIG. 3, and that some otheroperations may be omitted or only briefly described herein.

The method 300 starts with operation 302 in which a substrate afterchemical mechanical planarization is provided in accordance with someembodiments. In some embodiments, the substrate includes a siliconsubstrate. Alternatively, the substrate may include other elementarysemiconductor material such as, for example, germanium. The substratemay also include a compound semiconductor such as silicon carbide,gallium arsenide, indium arsenide, and indium phosphide. The substratemay include an alloy semiconductor such as silicon germanium, silicongermanium carbide, gallium arsenic phosphide, and gallium indiumphosphide. In one embodiment, the substrate includes an epitaxial layer.For example, the substrate may have an epitaxial layer overlying a bulksemiconductor. Furthermore, the substrate may include asemiconductor-on-insulator (SOI) structure. For example, the substratemay include a buried oxide (BOX) layer formed by a process such asseparation by implanted oxygen (SIMOX) or other suitable technique, suchas wafer bonding and grinding.

In some embodiments, the substrate also includes various p-type dopedregions and/or n-type doped regions, implemented by a process such asion implantation and/or diffusion. Those doped regions include n-well,p-well, lightly doped region (LDD), heavily doped source and drain(S/D), and various channel doping profiles configured to form variousintegrated circuit (IC) devices, such as a complimentarymetal-oxide-semiconductor field-effect transistor (CMOSFET), imagingsensor, and/or light emitting diode (LED). The substrate may furtherinclude other functional features such as a resistor or a capacitorformed in and on the substrate. The substrate further includes lateralisolation features provided to separate various devices formed in thesubstrate, for example shallow trench isolation (STI). The variousdevices in the substrate further include silicide disposed on S/D, gateand other device features for reduced contact resistance and enhanceprocess compatibility when coupled between devices through localinterconnections.

In an embodiment, the conductive feature can be also introduced on thesubstrate, which can be a source, drain or gate electrode.Alternatively, the conductive feature may be a silicide feature disposedon a source, drain or gate electrode typically from a sintering processintroduced by at least one of the processes including thermal heating,laser irradiation or ion beam mixing. The silicide feature may be formedon polysilicon gate (typically known as “polycide gate”) or by onsource/drain (typically known as “salicide”) by a self-aligned silicidetechnique. In another embodiment, the conductive feature may include anelectrode of a capacitor or one end of a resistor.

Excessive materials during the creation of aforementioned conductivefeatures, as well as other structures in integrated circuits, includinginterconnects, via structures, interlayer dielectrics, can be polishedout by a planarization process. A chemical-mechanical planarization(CMP) process is a typical planarization process, in which it utilizes achemical slurry formulation and mechanical polishing process to removeunwanted conductive or dielectric materials on the substrate, in orderto achieve a near-perfect flat and smooth surface. Because of the natureof this cleaning process, a variety of contaminants (e.g., trace metals,mobile ions and organic species) and abrasive materials (e.g., silicaand alumina) from the slurry can be introduced to the substrate surface.Therefore, it is important to remove contaminants and materials fromsubstrate after CMP, and reduce slurry residues to the required minimumlevel in order to potentially maximize device yields. Furthermore,particle contaminants can be also introduced by the cleaning parts, suchas brushes, pipes and container.

The method 300 continues with operation 304 in which the substrate fromthe CMP process is first pre-cleaning rinsed, in accordance with someembodiments. In certain embodiments, the pre-cleaning rinse is usingdeionized (DI) water. Referring to FIG. 1, the controller 114 closes thevalve on the chemical supply 104 and opens the valve on the DI waterrinse, which allows only DI water flows to the cleaning apparatus in thecleaning container 106.

The method 300 continues with operation 306 in which the substrate iscleaned in accordance with some embodiments. A typical post-CMP cleaningprocess is a wet cleaning process, comprising a magasonic cleaning, abrush scrubbing with hydrofluoric (HF) acid, a brush scrubbing withammonia hydroxide (NH4OH), and a spin-rinse-dry process. A megasoniccleaning is a form of non-contact cleaning method which is commonly usedto clean the substrate surface by creating an acoustic wave at megahertz(MHz) frequency range. The acoustic wave in the form of pressurefluctuations propagates through a liquid medium which is used to removeparticles from substrate surface by acoustic streaming and/or acousticcavitation. In some embodiments, the brush scrubbing is used forhydrodynamic removal of particulate contaminants and organic films fromthe substrate surface by rotation of a nylon or polypropylene brushacross the surface by creating a drag, electrostatic double layer andthermophoretic forces on the particles. The relative motion between thebrush and the substrate surface causes a thin liquid flow whichgenerates drag on the particle. In some embodiments, the cleaningprocess monitoring system described in this disclosure can be introducedto at least one of the aforementioned post-CMP cleaning processes inwhich a wet cleaning is used.

Different chemistries can be used to remove particle contamination withdifferent cleaning methods. The common chemicals used in brush scrubbinginclude deionized water, surfactants, ammonium hydroxide solution,isopropanol, methanol, hydrofluoric acid, citric acid, tetraethylammonium hydroxide (TMAH), a mixture of hydrogen peroxide, ammoniumhydroxide and water, and etc.

In some embodiments, a liquid CO2 cryogenic cleaning can be used, inwhich a directional and focused stream of gaseous CO2 from volumeexpansion is used to remove the particles by overcome the adhesionforces between the particle and the substrate. In some embodiments, theparticle detector 108 can be a gas particle counter.

Besides mechanical wiping and scrubbing, a non-contact post-CMP cleaningprocess can be also utilized. In some embodiments, a laser based removalmethod in which a pulsed energetic laser beam is used to heat locally ina thin liquid film on the substrate. The particle removal using thismethod is due to bubbles created by the superheating of the liquid. Insome embodiments, a plasma can be also used for cleaning. In someembodiments, a post-CMP cleaning process can be a combination ofaforementioned conventional and newly developed cleaning techniques.Modifications and implementations of the present system described inthis disclosure to contact and non-contact post-CMP cleaning process bydetecting particle levels in a downstream of cleaning solution (e.g.,liquid or gas) will be readily apparent to those skilled in the art.

The method 300 continues with operation 308 in which a concentration ofparticles of a particular size is detected and monitored in a downstreamof a cleaning solution in accordance with some embodiments. Referring toFIG. 1 again, the detection and monitoring is performed by a particledetector 108 integrated to the downstream of the cleaning solution. Insome embodiments, the particle detector 108 can be integrated to thedrain pipe before the liquid pump to avoid contamination from the pump110. In some embodiments, the particle detector 108 can be a laser basedparticle counter. The size and concentration can be determined bymeasuring the scattered light. In some embodiments, the particledetector 108 comprises an infrared light source according to thedetector used.

The method 300 continues with operation 310 in which the particleconcentration is compared to a pre-defined threshold value in accordancewith some embodiments. Referring to FIG. 2, the concentration of theparticle of various sizes is constantly measured during the post-CMPcleaning process and data is transmitted to the controller 114. If theconcentration of particles at a particular size is higher than thepre-defined threshold value, the method 300 continues with operation 306and 308 to allow the continuation of the cleaning process and theparticle concentration is continuously monitored. If the concentrationof particles at a particular size is lower than the pre-definedthreshold value, the cleaning process is then terminated and a secondsubstrate can be loaded after unloading the first substrate from thecleaning container 106.

Different from the traditional recipe-based cleaning method where acleaning time is fixed for different substrates with potentiallydifferent contamination levels, cleaning time can be customized for eachsubstrate individually using this present method. Therefore, this methodallows a reduction of cleaning time and thus chemical used. For example,a typical cleaning time in a brush scrubbing process is 40 seconds. If aparticle level can reach the threshold in 10 seconds, the cleaningprocess is terminated at 10 seconds to save time and chemicals. On theother hand, this method enforces an effective cleaning on substratesthat requires a longer cleaning time such that its surface contaminationcan be effectively controlled. Furthermore, this method can also reducecleaning related surface damages, e.g., scratches from brushes incontact mode, by reducing the cleaning time.

FIG. 4 illustrates an exemplary data 400 showing concentrations ofparticles of various sizes versus cleaning time, in accordance withvarious embodiments of the present disclosure. In certain embodiments,the measured particle concentration for three different sizes ofparticles each shows a peak corresponding to a sharp increase ofparticles numbers in the effluent in the drain pipe after the cleaningprocess is started. All three curves reach the peak at the same timeunder a fixed flow rate of 6 L/min, according to some embodiments. Thered curve 402 corresponds to particles in a size range of 1-5micrometers shows the highest concentration of ˜100000 counts/mL. Theblue curve 404 corresponds to particles in a size range of 5-10micrometers shows a peak particle concentration of 70000 counts/mL. Theblack curve 406 corresponds to particles in a size range of 10-20micrometers shows a peak particle concentration of 40000 counts/mL. Allthree curves show a slow decay of particle concentration and stabilizeat a concentration of 10000 counts/mL, which is the pre-definedthreshold value, at around 20 seconds. The cleaning process can be thenterminated once the measured particle concentration reaches thethreshold value.

In some embodiment, a cleaning process monitoring system, comprising: acleaning container comprising an inlet for receiving a cleaning solutionand an outlet for draining a waste solution; a particle detector coupledto the outlet and configured to measure a plurality of particleparameters associated with the waste solution so as to provide areal-time monitoring of the cleaning process; a pump coupled to thecleaning container through the outlet and configured to provide suctionto draw the waste solution through the cleaning system; and a controllercoupled to the pump and the particle detector and configured to receivethe plurality of particle parameters from the particle detector and tocontrol the cleaning system.

In another embodiment, a method for cleaning process monitoring,comprising: cleaning a surface of a first substrate in a cleaningcontainer with a cleaning solution, wherein the cleaning solution isreceived in an inlet and drained through an outlet; detecting aplurality of particle parameters in the cleaning solution in the outlet;comparing the plurality of particle parameters to a pre-defined endpoint value; and reconfiguring the cleaning process based on a resultfrom the comparing.

Yet, in another embodiment, a method for cleaning process monitoring,comprising: receiving a first wafer with a first surface for cleaning;cleaning the first surface of the first wafer using a cleaning solutionfrom a supply inlet; draining a waste solution from the first surface ofthe first wafer in a drain outlet; monitoring a first particleconcentration in the waste solution at a first time, wherein the firstparticle level is further compared to a pre-defined end point value; andterminating the cleaning process if a second particle level received ata second time is equal to or smaller than the pre-defined end pointvalue.

While various embodiments of the invention have been described above, itshould be understood that they have been presented by way of exampleonly, and not by way of limitation. Likewise, the various diagrams maydepict an example architectural or configuration, which are provided toenable persons of ordinary skill in the art to understand exemplaryfeatures and functions of the invention. Such persons would understand,however, that the invention is not restricted to the illustrated examplearchitectures or configurations, but can be implemented using a varietyof alternative architectures and configurations. Additionally, as wouldbe understood by persons of ordinary skill in the art, one or morefeatures of one embodiment can be combined with one or more features ofanother embodiment described herein. Thus, the breadth and scope of thepresent disclosure should not be limited by any of the above-describedexemplary embodiments.

It is also understood that any reference to an element herein using adesignation such as “first,” “second,” and so forth does not generallylimit the quantity or order of those elements. Rather, thesedesignations can be used herein as a convenient means of distinguishingbetween two or more elements or instances of an element. Thus, areference to first and second elements does not mean that only twoelements can be employed, or that the first element must precede thesecond element in some manner.

Additionally, a person having ordinary skill in the art would understandthat information and signals can be represented using any of a varietyof different technologies and techniques. For example, data,instructions, commands, information, signals, bits and symbols, forexample, which may be referenced in the above description can berepresented by voltages, currents, electromagnetic waves, magneticfields or particles, optical fields or particles, or any combinationthereof.

A person of ordinary skill in the art would further appreciate that anyof the various illustrative logical blocks, modules, processors, means,circuits, methods and functions described in connection with the aspectsdisclosed herein can be implemented by electronic hardware (e.g., adigital implementation, an analog implementation, or a combination ofthe two), firmware, various forms of program or design codeincorporating instructions (which can be referred to herein, forconvenience, as “software” or a “software module), or any combination ofthese techniques.

To clearly illustrate this interchangeability of hardware, firmware andsoftware, various illustrative components, blocks, modules, circuits,and steps have been described above generally in terms of theirfunctionality. Whether such functionality is implemented as hardware,firmware or software, or a combination of these techniques, depends uponthe particular application and design constraints imposed on the overallsystem. Skilled artisans can implement the described functionality invarious ways for each particular application, but such implementationdecisions do not cause a departure from the scope of the presentdisclosure. In accordance with various embodiments, a processor, device,component, circuit, structure, machine, module, etc. can be configuredto perform one or more of the functions described herein. The term“configured to” or “configured for” as used herein with respect to aspecified operation or function refers to a processor, device,component, circuit, structure, machine, module, etc. that is physicallyconstructed, programmed and/or arranged to perform the specifiedoperation or function.

Furthermore, a person of ordinary skill in the art would understand thatvarious illustrative logical blocks, modules, devices, components andcircuits described herein can be implemented within or performed by anintegrated circuit (IC) that can include a general purpose processor, adigital signal processor (DSP), an application specific integratedcircuit (ASIC), a field programmable gate array (FPGA) or otherprogrammable logic device, or any combination thereof. The logicalblocks, modules, and circuits can further include antennas and/ortransceivers to communicate with various components within the networkor within the device. A general purpose processor can be amicroprocessor, but in the alternative, the processor can be anyconventional processor, controller, or state machine. A processor canalso be implemented as a combination of computing devices, e.g., acombination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other suitable configuration to perform the functionsdescribed herein.

If implemented in software, the functions can be stored as one or moreinstructions or code on a computer-readable medium. Thus, the steps of amethod or algorithm disclosed herein can be implemented as softwarestored on a computer-readable medium. Computer-readable media includesboth computer storage media and communication media including any mediumthat can be enabled to transfer a computer program or code from oneplace to another. A storage media can be any available media that can beaccessed by a computer. By way of example, and not limitation, suchcomputer-readable media can include RAM, ROM, EEPROM, CD-ROM or otheroptical disk storage, magnetic disk storage or other magnetic storagedevices, or any other medium that can be used to store desired programcode in the form of instructions or data structures and that can beaccessed by a computer.

In this document, the term “module” as used herein, refers to software,firmware, hardware, and any combination of these elements for performingthe associated functions described herein. Additionally, for purpose ofdiscussion, the various modules are described as discrete modules;however, as would be apparent to one of ordinary skill in the art, twoor more modules may be combined to form a single module that performsthe associated functions according embodiments of the invention.

Additionally, memory or other storage, as well as communicationcomponents, may be employed in embodiments of the invention. It will beappreciated that, for clarity purposes, the above description hasdescribed embodiments of the invention with reference to differentfunctional units and processors. However, it will be apparent that anysuitable distribution of functionality between different functionalunits, processing logic elements or domains may be used withoutdetracting from the invention. For example, functionality illustrated tobe performed by separate processing logic elements, or controllers, maybe performed by the same processing logic element, or controller. Hence,references to specific functional units are only references to asuitable means for providing the described functionality, rather thanindicative of a strict logical or physical structure or organization.

Various modifications to the implementations described in thisdisclosure will be readily apparent to those skilled in the art, and thegeneral principles defined herein can be applied to otherimplementations without departing from the scope of this disclosure.Thus, the disclosure is not intended to be limited to theimplementations shown herein, but is to be accorded the widest scopeconsistent with the novel features and principles disclosed herein, asrecited in the claims below.

What is claimed is:
 1. A method for cleaning process monitoring,comprising: performing a chemical-mechanical planarization (CMP) processon a surface of a first substrate, wherein the CMP process utilizes achemical slurry and mechanical polishing to remove materials from thesurface of the first substrate; pre-cleaning the surface using deionizedwater; after the pre-cleaning, cleaning the surface of the firstsubstrate in a cleaning container with a cleaning solution, wherein thecleaning solution is received in an inlet and drained through an outlet;detecting a plurality of particle parameters in the cleaning solution inthe outlet; comparing the plurality of particle parameters to apre-defined end point value; and reconfiguring the cleaning processbased on a result from the comparing.
 2. The method of claim 1, whereinthe comparing is performed by a controller.
 3. The method of claim 2,wherein the controller is further configured to: receive the pluralityof particle parameters from the particle detector; configure a flow rateof the waste solution out of the outlet and a flow rate of the cleaningsolution into the inlet; and transmit the plurality of particleparameters to a host computer for display.
 4. The method of claim 1,wherein the detecting is performed by at least one particle detector. 5.The method of claim 4, wherein the at least one particle detectorcomprises at least one of the following detectors: optical detector,aerosol detector, liquid detector, solid detector, and laser detector.6. The method of claim 1, wherein the plurality of particle parameterscomprise particle size and particle concentration as a function ofcleaning time.
 7. The method of claim 1, wherein the pre-defined endpoint value equals to 10000 particles per milliliter in the wastesolution.
 8. The method of claim 4, wherein the pre-defined end pointvalue is configured based on size of particles.
 9. The method of claim1, wherein the reconfiguring comprises one of the following: terminatingthe cleaning process when the plurality of particle parameters aredetermined equal to or less than the pre-defined end point value, andcontinuing the cleaning process when the plurality of particleparameters are determined greater than the pre-defined end point value.10. A method for cleaning process monitoring, comprising: performing achemical-mechanical planarization (CMP) process on a surface of a firstsubstrate, wherein the CMP process utilizes a chemical slurry andmechanical polishing to remove materials from the surface of the firstsubstrate; pre-cleaning the surface using deionized water; after thepre-cleaning, megasonically cleaning the surface of the first substratein a liquid medium within a cleaning container, wherein the liquidmedium is received in an inlet and drained through an outlet; detectinga plurality of particle parameters in the liquid medium in the outlet;comparing the plurality of particle parameters to a pre-defined endpoint value; and reconfiguring the cleaning process based on a resultfrom the comparing.
 11. The method of claim 10, wherein the comparing isperformed by a controller.
 12. The method of claim 10, wherein thedetecting is performed by at least one particle detector.
 13. The methodof claim 12, wherein the at least one particle detector comprises atleast one of the following detectors: optical detector, aerosoldetector, liquid detector, solid detector, and laser detector.
 14. Themethod of claim 10, wherein the plurality of particle parameterscomprise particle size and particle concentration as a function ofcleaning time.
 15. The method of claim 10, wherein the pre-defined endpoint value equals to 10000 particles per milliliter in the wastesolution.
 16. The method of claim 10, wherein the pre-defined end pointvalue is configured based on size of particles.
 17. The method of claim1, wherein the reconfiguring comprises one of the following: terminatingthe cleaning process when the plurality of particle parameters aredetermined equal to or less than the pre-defined end point value, andcontinuing the cleaning process when the plurality of particleparameters are determined greater than the pre-defined end point value.18. A method for a cleaning process monitoring, comprising: performing achemical-mechanical planarization (CMP) process on a surface of a firstsubstrate, wherein the CMP process utilizes a chemical slurry andmechanical polishing to remove materials from the surface of the firstsubstrate; pre-cleaning the surface using deionized water; after thepre-cleaning, brush scrubbing the surface of the first substrate in acleaning container with a cleaning solution, wherein the cleaningsolution is received in an inlet and drained through an outlet;detecting a plurality of particle parameters in the cleaning solution inthe outlet; comparing the plurality of particle parameters to apre-defined end point value; and terminating the cleaning process whenthe plurality of particle parameters are determined equal to or lessthan the pre-defined end point value, and continuing the cleaningprocess when the plurality of particle parameters are determined greaterthan the pre-defined end point value.
 19. The method of claim 18 whereinthe detecting is performed by at least one particle detector.
 20. Themethod of claim 19, wherein the at least one particle detector comprisesat least one of the following detectors: optical detector, aerosoldetector, liquid detector, solid detector, and laser detector.
 21. Themethod of claim 18, wherein the plurality of particle parameterscomprise particle size and particle concentration as a function ofcleaning time.
 22. The method of claim 18, wherein the pre-defined endpoint value equals to 10000 particles per milliliter in the wastesolution, the 10000 particles meeting a pre-defined size criteria.